Role of cyclooxygenase-2-mediated prostaglandin E2-prostaglandin E receptor 4 signaling in cardiac reprogramming

Dual roles of the TLR2/TLR4/NLRP3-H-PGDS-PGD2 axis in regulating the inflammatory response in Escherichia coli-infected bovine bone marrow-derived macrophages and endometrial tissue

Endometritis in dairy cows is associated with pathogenic microorganisms, local inflammatory injuries, and uterine microecological disorders. Escherichia coli (E. coli) is the primary pathogen responsible for bovine endometritis onset; however, the underlying pathomechanisms remain unclear. In this study, we aimed to investigate E. coli-induced endometritis mechanisms in dairy cows using bovine bone marrow-derived macrophages and endometrial tissue. Following E. coli infection of macrophages, we observed a significant increase in the mRNA expression levels of innate immune recognition receptors, including toll-like receptor 2 (TLR2), toll-like receptor 4 (TLR4), and nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3), as well as prostaglandin D2 (PGD2)-related enzymes (cyclooxygenase-2 and hematopoietic prostaglandin D synthase). Furthermore, the secretion of PGD2, a major mediator of inflammation, was markedly upregulated. In E. coli-infected macrophages, TLR2, TLR4, and NLRP3 increased the secretion of inflammatory mediators, including PGD2, by activating mitogen-activated protein kinase (MAPK) and nuclear factor-κB (NF-κB). This lead to enhanced inflammatory response. During early E. coli infection, PGD2 inhibitors reduced the secretion of inflammatory mediators by modulating MAPK and NF-κB pathway activation and enhancing macrophage bacterial killing, thereby alleviating endometrial tissue damage in dairy cows. In contrast, in the later stages of infection, PGD2 inhibitors exacerbated the inflammatory response and impaired the killing capacity of macrophages, which lead to increased endometrial tissue damage. Therefore, our findings highlight that TLR2, TLR4, and NLRP3 are pivotal in regulating PGD2 secretion during E. coli-induced endometritis in dairy cows. PGD2 had a pro-inflammatory effect in the early stages of E. coli infection and anti-inflammatory effects in the later stages. These findings can help develop strategies benefiting endometritis treatment.

Cell reprogramming: methods, mechanisms and applications

Cell reprogramming represents a powerful approach to achieve the conversion cells of one type into cells of another type of interest, which has substantially changed the landscape in the field of developmental biology, regenerative medicine, disease modeling, drug discovery and cancer immunotherapy. Cell reprogramming is a complex and ordered process that involves the coordination of transcriptional, epigenetic, translational and metabolic changes. Over the past two decades, a range of questions regarding the facilitators/barriers, the trajectories, and the mechanisms of cell reprogramming have been extensively investigated. This review summarizes the recent advances in cell reprogramming mediated by transcription factors or chemical molecules, followed by elaborating on the important roles of biophysical cues in cell reprogramming. Additionally, this review will detail our current understanding of the mechanisms that govern cell reprogramming, including the involvement of the recently discovered biomolecular condensates. Finally, the review discusses the broad applications and future directions of cell reprogramming in developmental biology, disease modeling, drug development, regenerative/rejuvenation therapy, and cancer immunotherapy.

Decoding the epigenetic and transcriptional basis of direct cardiac reprogramming

Heart disease, particularly resulting from myocardial infarction (MI), continues to be a leading cause of mortality, largely due to the limited regenerative capacity of the human heart. Current therapeutic approaches seek to generate new cardiomyocytes from alternative sources. Direct cardiac reprogramming, which converts fibroblasts into induced cardiomyocytes (iCMs), offers a promising alternative by enabling in situ cardiac regeneration and minimizing tumorigenesis concerns. Here we review recent advancements in the understanding of transcriptional and epigenetic mechanisms underlying cardiac reprogramming, with a focus on key early-stage molecular events, including epigenetic barriers and regulatory mechanisms that facilitate reprogramming. Despite substantial progress, human cardiac fibroblast reprogramming and iCM maturation remain areas for further exploration. We also discuss the combinatorial roles of reprogramming factors in governing transcriptional and epigenetic changes. This review consolidates current knowledge and proposes future directions for promoting the translational potential of cardiac reprogramming techniques.

Direct fibroblast reprogramming: an emerging strategy for treating organic fibrosis

Direct reprogramming has garnered considerable attention due to its capacity to directly convert differentiated cells into desired cells. Fibroblasts are frequently employed in reprogramming studies due to their abundance and accessibility. However, they are also the key drivers in the progression of fibrosis, a pathological condition characterized by excessive extracellular matrix deposition and tissue scarring. Furthermore, the initial stage of reprogramming typically involves deactivating fibrotic pathways. Hence, direct reprogramming offers a valuable method to regenerate target cells for tissue repair while simultaneously reducing fibrotic tendencies. Understanding the link between reprogramming and fibrosis could help develop effective strategies to treat damaged tissue with a potential risk of fibrosis. This review summarizes the advances in direct reprogramming and reveals their anti-fibrosis effects in various organs such as the heart, liver, and skin. Furthermore, we dissect the mechanisms of reprogramming influenced by fibrotic molecules including TGF-β signaling, mechanical signaling, inflammation signaling, epigenetic modifiers, and metabolic regulators. Innovative methods for fibroblast reprogramming like small molecules, CRISPRa, modified mRNA, and the challenges of cellular heterogeneity and senescence faced by in vivo direct reprogramming, are also discussed.

Macrophages suppress cardiac reprogramming of fibroblasts in vivo via IFN-mediated intercellular self-stimulating circuit

Direct conversion of cardiac fibroblasts (CFs) to cardiomyocytes (CMs) in vivo to regenerate heart tissue is an attractive approach. After myocardial infarction (MI), heart repair proceeds with an inflammation stage initiated by monocytes infiltration of the infarct zone establishing an immune microenvironment. However, whether and how the MI microenvironment influences the reprogramming of CFs remains unclear. Here, we found that in comparison with cardiac fibroblasts (CFs) cultured in vitro, CFs that transplanted into infarct region of MI mouse models resisted to cardiac reprogramming. RNA-seq analysis revealed upregulation of interferon (IFN) response genes in transplanted CFs, and subsequent inhibition of the IFN receptors increased reprogramming efficiency in vivo. Macrophage-secreted IFN-β was identified as the dominant upstream signaling factor after MI. CFs treated with macrophage-conditioned medium containing IFN-β displayed reduced reprogramming efficiency, while macrophage depletion or blocking the IFN signaling pathway after MI increased reprogramming efficiency in vivo. Co-IP, BiFC and Cut-tag assays showed that phosphorylated STAT1 downstream of IFN signaling in CFs could interact with the reprogramming factor GATA4 and inhibit the GATA4 chromatin occupancy in cardiac genes. Furthermore, upregulation of IFN-IFNAR-p-STAT1 signaling could stimulate CFs secretion of CCL2/7/12 chemokines, subsequently recruiting IFN-β-secreting macrophages. Together, these immune cells further activate STAT1 phosphorylation, enhancing CCL2/7/12 secretion and immune cell recruitment, ultimately forming a self-reinforcing positive feedback loop between CFs and macrophages via IFN-IFNAR-p-STAT1 that inhibits cardiac reprogramming in vivo. Cumulatively, our findings uncover an intercellular self-stimulating inflammatory circuit as a microenvironmental molecular barrier of in situ cardiac reprogramming that needs to be overcome for regenerative medicine applications.

Control of cell fate upon transcription factor-driven cardiac reprogramming

Adult mammals are susceptible to substantial cardiomyocyte (CM) loss following various cardiac diseases due to the limited capacity of CM proliferation and regeneration. Recently, direct cardiac reprogramming, converting fibroblasts into induced CMs, has been achieved both in vitro and in vivo through forced expression of transcription factors (TFs). This review encapsulates the advancements made in enhancing reprogramming efficiency and underlying molecular mechanisms. It covers the optimization of TF-based reprogramming cocktails and in vivo delivery platform and recently identified regulators in enhancing reprogramming efficiency. In addition, we discuss recent insights into the molecular mechanisms of direct cardiac reprogramming from single-cell omics analyses. Finally, we briefly touch on remaining challenges and prospective direction of this field.

The role of cardiomyocyte senescence in cardiovascular diseases: A molecular biology update

Cardiovascular diseases (CVD) are the leading cause of death worldwide, and advanced age is a main contributor to the prevalence of CVD. Cellular senescence is an irreversible state of cell cycle arrest that occurs in old age or after cells encounter various stresses. Senescent cells not only result in the reduction of cellular function, but also produce senescence-associated secretory phenotype (SASP) to affect surrounding cells and tissue microenvironment. There is increasing evidence that the gradual accumulation of senescent cardiomyocytes is causally involved in the decline of cardiovascular system function. To highlight the role of senescent cardiomyocytes in the pathophysiology of age-related CVD, we first introduced that senescent cardiomyoyctes can be identified by structural changes and several senescence-associated biomarkers. We subsequently provided a comprehensive summary of existing knowledge, outlining the compelling evidence on the relationship between senescent cardiomyocytes and age-related CVD phenotypes. In addition, we discussed that the significant therapeutic potential represented by the prevention of accelerated senescent cardiomyocytes, and the current status of some existing geroprotectors in the prevention and treatment of age-related CVD. Together, the review summarized the role of cardiomyocyte senescence in CVD, and explored the molecular knowledge of senescent cardiomyocytes and their potential clinical significance in developing senescent-based therapies, thereby providing important insights into their biology and potential therapeutic exploration.

Dedifferentiation-like reprogramming of degenerative nucleus pulposus cells into notochordal-like cells by defined factors

The extensive degeneration of functional somatic cells and the depletion of endogenous stem/progenitor populations present significant challenges to tissue regeneration in degenerative diseases. Currently, a cellular reprogramming approach enabling directly generating corresponding progenitor populations from degenerative somatic cells remains elusive. The present study focused on intervertebral disc degeneration (IVDD) and identified a three-factor combination (OCT4, FOXA2, TBXT [OFT]) that could induce the dedifferentiation-like reprogramming of degenerative nucleus pulposus cells (dNPCs) toward induced notochordal-like cells (iNCs). Single-cell transcriptomics dissected the transitions of cell identity during reprogramming. Further, OCT4 was found to directly interact with bromodomain PHD-finger transcription factor to remodel the chromatin during the early phases, which was crucial for initiating this dedifferentiation-like reprogramming. In rat models, intradiscal injection of adeno-associated virus carrying OFT generated iNCs from in situ dNPCs and reversed IVDD. These results collectively present a proof-of-concept for dedifferentiation-like reprogramming of degenerated somatic cells into corresponding progenitors through the development of a factor-based strategy, providing a promising approach for regeneration in degenerative disc diseases.

Next-generation direct reprogramming

Tissue repair is significantly compromised in the aging human body resulting in critical disease conditions (such as myocardial infarction or Alzheimer's disease) and imposing a tremendous burden on global health. Reprogramming approaches (partial or direct reprogramming) are considered fruitful in addressing this unmet medical need. However, the efficacy, cellular maturity and specific targeting are still major challenges of direct reprogramming. Here we describe novel approaches in direct reprogramming that address these challenges. Extracellular signaling pathways (Receptor tyrosine kinases, RTK and Receptor Serine/Theronine Kinase, RSTK) and epigenetic marks remain central in rewiring the cellular program to determine the cell fate. We propose that modern protein design technologies (AI-designed minibinders regulating RTKs/RSTK, epigenetic enzymes, or pioneer factors) have potential to solve the aforementioned challenges. An efficient transdifferentiation/direct reprogramming may in the future provide molecular strategies to collectively reduce aging, fibrosis, and degenerative diseases.

DIRECTEUR: transcriptome-based prediction of small molecules that replace transcription factors for direct cell conversion

MOTIVATION

Direct reprogramming (DR) is a process that directly converts somatic cells to target cells. Although DR via small molecules is safer than using transcription factors (TFs) in terms of avoidance of tumorigenic risk, the determination of DR-inducing small molecules is challenging.

RESULTS

Here we present a novel in silico method, DIRECTEUR, to predict small molecules that replace TFs for DR. We extracted DR-characteristic genes using transcriptome profiles of cells in which DR was induced by TFs, and performed a variant of simulated annealing to explore small molecule combinations with similar gene expression patterns with DR-inducing TFs. We applied DIRECTEUR to predicting combinations of small molecules that convert fibroblasts into neurons or cardiomyocytes, and were able to reproduce experimentally verified and functionally related molecules inducing the corresponding conversions. The proposed method is expected to be useful for practical applications in regenerative medicine.

AVAILABILITY AND IMPLEMENTATION

The code and data are available at the following link: https://github.com/HamanoLaboratory/DIRECTEUR.git.

Cardiac Transcription Factors and Regulatory Networks

Cardiac development is a fine-tuned process governed by complex transcriptional networks, in which transcription factors (TFs) interact with other regulatory layers. In this chapter, we introduce the core cardiac TFs including Gata, Hand, Nkx2, Mef2, Srf, and Tbx. These factors regulate each other's expression and can also act in a combinatorial manner on their downstream targets. Their disruption leads to various cardiac phenotypes in mice, and mutations in humans have been associated with congenital heart defects. In the second part of the chapter, we discuss different levels of regulation including cis-regulatory elements, chromatin structure, and microRNAs, which can interact with transcription factors, modulate their function, or are downstream targets. Finally, examples of disturbances of the cardiac regulatory network leading to congenital heart diseases in human are provided.

Fibroblast Reprogramming in Cardiac Repair

Cardiovascular disease is one of the major causes of death worldwide. Limited proliferative capacity of adult mammalian cardiomyocytes has prompted researchers to exploit regenerative therapy after myocardial injury, such as myocardial infarction, to attenuate heart dysfunction caused by such injury. Direct cardiac reprogramming is a recently emerged promising approach to repair damaged myocardium by directly converting resident cardiac fibroblasts into cardiomyocyte-like cells. The achievement of in vivo direct reprogramming of fibroblasts has been shown, by multiple laboratories independently, to improve cardiac function and mitigate fibrosis post-myocardial infarction, which holds great potential for clinical application. There have been numerous pieces of valuable work in both basic and translational research to enhance our understanding and continued refinement of direct cardiac reprogramming in recent years. However, there remain many challenges to overcome before we can truly take advantage of this technique to treat patients with ischemic cardiac diseases. Here, we review recent progress of fibroblast reprogramming in cardiac repair, including the optimization of several reprogramming strategies, mechanistic exploration, and translational efforts, and we make recommendations for future research to further understand and translate direct cardiac reprogramming from bench to bedside. Challenges relating to these efforts will also be discussed.

Cell Reprogramming and Differentiation Utilizing Messenger RNA for Regenerative Medicine

The COVID-19 pandemic generated interest in the medicinal applications of messenger RNA (mRNA). It is expected that mRNA will be applied, not only to vaccines, but also to regenerative medicine. The purity of mRNA is important for its medicinal applications. However, the current mRNA synthesis techniques exhibit problems, including the contamination of undesired 5'-uncapped mRNA and double-stranded RNA. Recently, our group developed a completely capped mRNA synthesis technology that contributes to the progress of mRNA research. The introduction of chemically modified nucleosides, such as N1-methylpseudouridine and 5-methylcytidine, has been reported by Karikó and Weissman, opening a path for the practical application of mRNA for vaccines and regenerative medicine. Yamanaka reported the production of induced pluripotent stem cells (iPSCs) by introducing four types of genes using a retrovirus vector. iPSCs are widely used for research on regenerative medicine and the preparation of disease models to screen new drug candidates. Among the Yamanaka factors, Klf4 and c-Myc are oncogenes, and there is a risk of tumor development if these are integrated into genomic DNA. Therefore, regenerative medicine using mRNA, which poses no risk of genome insertion, has attracted attention. In this review, the author summarizes techniques for synthesizing mRNA and its application in regenerative medicine.

Recent advances and future prospects in direct cardiac reprogramming

Cardiovascular disease remains a leading cause of death worldwide despite important advances in modern medical and surgical therapies. As human adult cardiomyocytes have limited regenerative ability, cardiomyocytes lost after myocardial infarction are replaced by fibrotic scar tissue, leading to cardiac dysfunction and heart failure. To replace lost cardiomyocytes, a promising approach is direct cardiac reprogramming, in which cardiac fibroblasts are transdifferentiated into induced cardiomyocyte-like cells (iCMs). Here we review cardiac reprogramming cocktails (including transcription factors, microRNAs and small molecules) that mediate iCM generation. We also highlight mechanistic studies exploring the barriers to and facilitators of this process. We then review recent progress in iCM reprogramming, with a focus on single-cell '-omics' research. Finally, we discuss obstacles to clinical application.

Partial in vivo reprogramming enables injury-free intestinal regeneration via autonomous Ptgs1 induction

Tissue regeneration after injury involves the dedifferentiation of somatic cells, a natural adaptive reprogramming that leads to the emergence of injury-responsive cells with fetal-like characteristics. However, there is no direct evidence that adaptive reprogramming involves a shared molecular mechanism with direct cellular reprogramming. Here, we induced dedifferentiation of intestinal epithelial cells using OSKM (Oct4, Sox2, Klf4, and c-Myc) in vivo. The OSKM-induced forced dedifferentiation showed similar molecular features of intestinal regeneration, including a transition from homeostatic cell types to injury-responsive-like cell types. These injury-responsive-like cells, sharing gene signatures of revival stem cells and atrophy-induced villus epithelial cells, actively assisted tissue regeneration following damage. In contrast to normal intestinal regeneration involving Ptgs2 induction, the OSKM promotes autonomous production of prostaglandin E2 via epithelial Ptgs1 expression. These results indicate prostaglandin synthesis is a common mechanism for intestinal regeneration but involves a different enzyme when partial reprogramming is applied to the intestinal epithelium.

Cellular reprogramming of fibroblasts in heart regeneration

Myocardial infarction causes the loss of cardiomyocytes and the formation of cardiac fibrosis due to the activation of cardiac fibroblasts, leading to cardiac dysfunction and heart failure. Unfortunately, current therapeutic interventions can only slow the disease progression. Furthermore, they cannot fully restore cardiac function, likely because the adult human heart lacks sufficient capacity to regenerate cardiomyocytes. Therefore, intensive efforts have focused on developing therapeutics to regenerate the damaged heart. Several strategies have been intensively investigated, including stimulation of cardiomyocyte proliferation, transplantation of stem cell-derived cardiomyocytes, and conversion of fibroblasts into cardiac cells. Resident cardiac fibroblasts are critical in the maintenance of the structure and contractility of the heart. Fibroblast plasticity makes this type of cells be reprogrammed into many cell types, including but not limited to induced pluripotent stem cells, induced cardiac progenitor cells, and induced cardiomyocytes. Fibroblasts have become a therapeutic target due to their critical roles in cardiac pathogenesis. This review summarizes the reprogramming of fibroblasts into induced pluripotent stem cell-derived cardiomyocytes, induced cardiac progenitor cells, and induced cardiomyocytes to repair a damaged heart, outlines recent findings in utilizing fibroblast-derived cells for heart regeneration, and discusses the limitations and challenges.

Positive effect of miR-2392 on fibroblast to cardiomyocyte-like cell fate transition: an in silico and in vitro study

INTRODUCTION

Somatic cell fate transition is now gained great importance in tissue regeneration. Currently, research is focused on heart tissue regeneration by reprogramming diverse cells into cardiomyocyte-like cells. Here, we examined the possible effect of miRNAs on the transdifferentiation of fibroblasts into cardiomyocyte-like cells.

METHODS

First heart-specific miRNAs were identified by comparing the gene expression profiles of heart tissue to other body tissues using bioinformatic techniques. After identifying heart-specific miRNAs, their cellular and molecular functions were studied using the miRWalk and miRBase databases. Then the candidate miRNA was cloned into a lentiviral vector. Following, human dermal fibroblasts were cultured and treated with compounds forskolin, valproic acid, and CHIR99021. After 24 h, the lentivector harboring miRNA gene was transfected into the cells to initiate the transdifferentiation process. Finally, after a two-week treatment period, the efficiency of transdifferentiation was examined by inspecting the appearance of the cells and measuring the expression levels of cardiac genes and proteins using RT-qPCR and immunocytochemistry techniques.

RESULTS

Nine miRNAs were identified with higher expression in the heart. The miR-2392 was nominated as the candidate miRNA due to its function and specific expression in the heart. This miRNA has a direct connection with genes involved in cell growth and differentiation; e.g., MAPK and Wnt signaling pathways. According to in vitro results cardiac genes and proteins demonstrated an increase in expression in the fibroblasts that simultaneously received the three chemicals and miR-2392.

CONCLUSION

Considering the ability of miR-2392 to induce the expression of cardiac genes and proteins in fibroblast cells, it can induce fibroblasts to differentiate into cardiomyocyte-like cells. Therefore, miR-2392 could be further optimized for cardiomyocyte regeneration, tissue repair, and drug design studies.

Targeting neuro-immune systems to achieve cardiac tissue repair following myocardial infarction: A review of therapeutic approaches from in-vivo preclinical to clinical studies

Myocardial healing following myocardial infarction (MI) toward either functional tissue repair or excessive scarring/heart failure, may depend on a complex interplay between nervous and immune system responses, myocardial ischemia/reperfusion injury factors, as well as genetic and epidemiological factors. Hence, enhancing cardiac repair post MI may require a more patient-specific approach targeting this complex interplay and not just the heart, bearing in mind that the dysregulation or modulation of just one of these systems or some of their mechanisms may determine the outcome either toward functional repair or toward heart failure. In this review we have elected to focus on existing preclinical and clinical in-vivo studies aimed at testing novel therapeutic approaches targeting the nervous and immune systems to trigger myocardial healing toward functional tissue repair. To this end, we have only selected clinical and preclinical in-vivo studies reporting on novel treatments targeting neuro-immune systems to ultimately treat MI. Next, we have grouped and reported treatments under each neuro-immune system. Finally, for each treatment we have assessed and reported the results of each clinical/preclinical study and then discussed their results collectively. This structured approach has been followed for each treatment discussed. To keep this review focused, we have deliberately omitted to cover other important and related research areas such as myocardial ischemia/reperfusion injury, cell and gene therapies as well as any ex-vivo and in-vitro studies. The review indicates that some of the treatments targeting the neuro-immune/inflammatory systems appear to induce beneficial effects remotely on the healing heart post MI, warranting further validation. These remote effects on the heart also indicates the presence of an overarching synergic response occurring across the nervous and immune systems in response to acute MI, which appear to influence cardiac tissue repair in different ways depending on age and timing of treatment delivery following MI. The cumulative evidence arising from this review allows also to make informed considerations on safe as opposed to detrimental treatments, and within the safe treatments to ascertain those associated with conflicting or supporting preclinical data, and those warranting further validation.

Reprogramming of cardiac cell fate as a therapeutic strategy for ischemic heart disease

Direct reprogramming of resident cardiac fibroblasts to induced cardiomyocytes is an attractive therapeutic strategy to restore function and remuscularize the injured heart. The cardiac transcription factors Gata4, Mef2c, and Tbx5 have been the mainstay of direct cardiac reprogramming strategies for the past decade. Yet, recent discoveries have identified alternative epigenetic factors capable of reprogramming human cells in the absence of these canonical factors. Further, single-cell genomics evaluating cellular maturation and epigenetics in the setting of injury and heart failure models following reprogramming have continued to inform the mechanistic underpinnings of this process and point toward future areas of discovery for the field. These discoveries and others covered in this review have provided complementary approaches that further enhance the effectiveness of reprogramming as a means of promoting cardiac regeneration following myocardial infarction and heart failure.

Conserved transcription factors promote cell fate stability and restrict reprogramming potential in differentiated cells

Defining the mechanisms safeguarding cell fate identity in differentiated cells is crucial to improve 1) - our understanding of how differentiation is maintained in healthy tissues or altered in a disease state, and 2) - our ability to use cell fate reprogramming for regenerative purposes. Here, using a genome-wide transcription factor screen followed by validation steps in a variety of reprogramming assays (cardiac, neural and iPSC in fibroblasts and endothelial cells), we identified a set of four transcription factors (ATF7IP, JUNB, SP7, and ZNF207 [AJSZ]) that robustly opposes cell fate reprogramming in both lineage and cell type independent manners. Mechanistically, our integrated multi-omics approach (ChIP, ATAC and RNA-seq) revealed that AJSZ oppose cell fate reprogramming by 1) - maintaining chromatin enriched for reprogramming TF motifs in a closed state and 2) - downregulating genes required for reprogramming. Finally, KD of AJSZ in combination with MGT overexpression, significantly reduced scar size and improved heart function by 50%, as compared to MGT alone post-myocardial infarction. Collectively, our study suggests that inhibition of barrier to reprogramming mechanisms represents a promising therapeutic avenue to improve adult organ function post-injury.

Extracellular Vesicles Produced by the Cardiac Microenvironment Carry Functional Enzymes to Produce Lipid Mediators In Situ

The impact of the polyunsaturated fatty acids (PUFAs) at physiological concentrations on the composition of eicosanoids transported within the extracellular vesicles (EVs) of rat bone marrow mesenchymal stem cells and cardiomyoblasts was reported by our group in 2020. The aim of this article was to extend this observation to cells from the cardiac microenvironment involved in the processes of inflammation, namely mouse J774 macrophages and rat heart mesenchymal stem cells cMSCs. Moreover, to enhance our capacity to understand the paracrine exchange between these orchestrators of cardiac inflammation, we investigated some machinery involved in the eicosanoid’s synthesis transported by the EVs produced by these cells (including the two formerly described cells: bone marrow mesenchymal stem cells BM-MSC and cardiomyoblasts H9c2). We analyzed the oxylipin and the enzymatic content of the EVs collected from cell cultures supplemented (or not) with PUFAs. We prove that large eicosanoid profiles are exported in the EVs by the cardiac microenvironment cells, but also that these EVs carry some critical and functional biosynthetic enzymes, allowing them to synthesize inflammation bioactive compounds by sensing their environment. Moreover, we demonstrate that these are functional. This observation reinforces the hypothesis that EVs are key factors in paracrine signaling, even in the absence of the parent cell. We also reveal a macrophage-specific behavior, as we observed a radical change in the lipid mediator profile when small EVs derived from J774 cells were exposed to PUFAs. To summarize, we prove that the EVs, due to the carried functional enzymes, can alone produce bioactive compounds, in the absence of the parent cell, by sensing their environment. This makes them potential circulating monitoring entities.

Metabolic landscape in cardiac aging: insights into molecular biology and therapeutic implications

Cardiac aging is evident by a reduction in function which subsequently contributes to heart failure. The metabolic microenvironment has been identified as a hallmark of malignancy, but recent studies have shed light on its role in cardiovascular diseases (CVDs). Various metabolic pathways in cardiomyocytes and noncardiomyocytes determine cellular senescence in the aging heart. Metabolic alteration is a common process throughout cardiac degeneration. Importantly, the involvement of cellular senescence in cardiac injuries, including heart failure and myocardial ischemia and infarction, has been reported. However, metabolic complexity among human aging hearts hinders the development of strategies that targets metabolic susceptibility. Advances over the past decade have linked cellular senescence and function with their metabolic reprogramming pathway in cardiac aging, including autophagy, oxidative stress, epigenetic modifications, chronic inflammation, and myocyte systolic phenotype regulation. In addition, metabolic status is involved in crucial aspects of myocardial biology, from fibrosis to hypertrophy and chronic inflammation. However, further elucidation of the metabolism involvement in cardiac degeneration is still needed. Thus, deciphering the mechanisms underlying how metabolic reprogramming impacts cardiac aging is thought to contribute to the novel interventions to protect or even restore cardiac function in aging hearts. Here, we summarize emerging concepts about metabolic landscapes of cardiac aging, with specific focuses on why metabolic profile alters during cardiac degeneration and how we could utilize the current knowledge to improve the management of cardiac aging.

Development of direct cardiac reprogramming for clinical applications

The incidence of cardiovascular diseases is increasing worldwide, and cardiac regenerative therapy has great potential as a new treatment strategy, especially for ischemic heart disease. Direct cardiac reprogramming is a promising new cardiac regenerative therapy that uses defined factors to induce transdifferentiation of endogenous cardiac fibroblasts (CFs) into induced cardiomyocyte-like cells (iCMs). In vivo reprogramming is expected to restore lost cardiac function without necessitating cardiac transplantation by converting endogenous CFs that exist abundantly in cardiac tissues directly into iCMs. Indeed, we and other groups have demonstrated that in vivo cardiac reprogramming improves cardiac contractile function and reduces scar area after acute myocardial infarction (MI). Recently, we demonstrated that in vivo cardiac reprogramming is an innovative cardiac regenerative therapy that not only regenerates the myocardium, but also reverses fibrosis by inducing the quiescence of pro-fibrotic fibroblasts, thereby improving heart failure in chronic MI. In this review, we summarize the recent progresses in in vivo cardiac reprogramming, and discuss its prospects for future clinical applications and the challenges of direct human reprogramming, which has been a longstanding issue.

Direct Reprogramming Improves Cardiac Function and Reverses Fibrosis in Chronic Myocardial Infarction

BACKGROUND

Because adult cardiomyocytes have little regenerative capacity, resident cardiac fibroblasts (CFs) synthesize extracellular matrix after myocardial infarction (MI) to form fibrosis, leading to cardiac dysfunction and heart failure. Therapies that can regenerate the myocardium and reverse fibrosis in chronic MI are lacking. The overexpression of cardiac transcription factors, including Mef2c/Gata4/Tbx5/Hand2 (MGTH), can directly reprogram CFs into induced cardiomyocytes (iCMs) and improve cardiac function under acute MI. However, the ability of in vivo cardiac reprogramming to repair chronic MI with established scars is undetermined.

METHODS

We generated a novel Tcf21^iCre/reporter/MGTH2A transgenic mouse system in which tamoxifen treatment could induce both MGTH and reporter expression in the resident CFs for cardiac reprogramming and fibroblast lineage tracing. We first tested the efficacy of this transgenic system in vitro and in vivo for acute MI. Next, we analyzed in vivo cardiac reprogramming and fusion events under chronic MI using Tcf21^iCre/Tomato/MGTH2A and Tcf21^iCre/mTmG/MGTH2A mice, respectively. Microarray and single-cell RNA sequencing were performed to determine the mechanism of cardiac repair by in vivo reprogramming.

RESULTS

We confirmed the efficacy of transgenic in vitro and in vivo cardiac reprogramming for acute MI. In chronic MI, in vivo cardiac reprogramming converted ≈2% of resident CFs into iCMs, in which a majority of iCMs were generated by means of bona fide cardiac reprogramming rather than by fusion with cardiomyocytes. Cardiac reprogramming significantly improved myocardial contraction and reduced fibrosis in chronic MI. Microarray analyses revealed that the overexpression of MGTH activated cardiac program and concomitantly suppressed fibroblast and inflammatory signatures in chronic MI. Single-cell RNA sequencing demonstrated that resident CFs consisted of 7 subclusters, in which the profibrotic CF population increased under chronic MI. Cardiac reprogramming suppressed fibroblastic gene expression in chronic MI by means of conversion of profibrotic CFs to a quiescent antifibrotic state. MGTH overexpression induced antifibrotic effects partly by suppression of Meox1, a central regulator of fibroblast activation.

CONCLUSIONS

These results demonstrate that cardiac reprogramming could repair chronic MI by means of myocardial regeneration and reduction of fibrosis. These findings present opportunities for the development of new therapies for chronic MI and heart failure.

Direct cardiac reprogramming: Toward the era of multi-omics analysis

Limited regenerative capacity of adult cardiomyocytes precludes heart repair and regeneration after cardiac injury. Direct cardiac reprograming that converts scar-forming cardiac fibroblasts (CFs) into functional induced-cardiomyocytes (iCMs) offers promising potential to restore heart structure and heart function. Significant advances have been achieved in iCM reprogramming using genetic and epigenetic regulators, small molecules, and delivery strategies. Recent researches on the heterogeneity and reprogramming trajectories elucidated novel mechanisms of iCM reprogramming at single cell level. Here, we review recent progress in iCM reprogramming with a focus on multi-omics (transcriptomic, epigenomic and proteomic) researches to investigate the cellular and molecular machinery governing cell fate conversion. We also highlight the future potential using multi-omics approaches to dissect iCMs conversion for clinal applications.

Effect of CYP2C9, PTGS-1 and PTGS-2 gene polymorphisms on the efficiency and safety of postoperative analgesia with ketoprofen

OBJECTIVES

Patients undergoing cardiac surgery develop post-sternotomy pain syndrome. The aim of this study was evaluation of the influence of CYP2C9, PTGS-1 and PTGS-2 genes polymorphisms on the efficacy and safety of postoperative analgesia with ketoprofen in patients with coronary artery disease after cardiac surgery.

METHODS

The study included 90 patients undergoing cardiac surgery. A real-time polymerase chain reaction was used for the detection of single nucleotide polymorphisms (SNP). Pain intensity was measured by the Numeric Rating Scale (NRS). Dyspeptic symptoms were evaluated using the Gastrointestinal Symptom Rating Scale (GSRS). Acute kidney injury (AKI) was determined by Kidney Disease Improving Global Outcomes criteria.

RESULTS

Pain intensity by the NRS score was significantly higher in patients with CYP2C9*3 АA genotype compared to АC genotype: 7 [1,10] and 6 [2,7] (p=0.003); 7 [1,10] and 6 [2,7] (p=0.04); 6 [0; 10] and 5 [2,6] (p=0.04); 5 [0; 8] and 3 [0; 8] (p=0.02), on days 1, 2, 3 and 5 in the postoperative period, respectively. GSRS score was higher in patients with CYP2C9*2 CT genotype compared to CС genotype: 19 [15; 42] and 18 [15,36] (p=0.04), respectively. There were no significant differences in the pain intensity, dyspepsia severity and AKI frequency in patients with homozygous and heterozygous genotypes for PTGS-1 rs10306135, PTGS-1 rs12353214, PTGS-2 rs20417.

CONCLUSIONS

CYP2C9*3 and CYP2C9*2 gene polymorphisms may affect efficacy and safety of postoperative analgesia with ketoprofen in patients with coronary artery disease after cardiac surgery.

Small compound-based direct cell conversion with combinatorial optimization of pathway regulations

MOTIVATION

Direct cell conversion, direct reprogramming (DR), is an innovative technology that directly converts source cells to target cells without bypassing induced pluripotent stem cells. The use of small compounds (e.g. drugs) for DR can help avoid carcinogenic risk induced by gene transfection; however, experimentally identifying small compounds remains challenging because of combinatorial explosion.

RESULTS

In this article, we present a new computational method, COMPRENDRE (combinatorial optimization of pathway regulations for direct reprograming), to elucidate the mechanism of small compound-based DR and predict new combinations of small compounds for DR. We estimated the potential target proteins of DR-inducing small compounds and identified a set of target pathways involving DR. We identified multiple DR-related pathways that have not previously been reported to induce neurons or cardiomyocytes from fibroblasts. To overcome the problem of combinatorial explosion, we developed a variant of a simulated annealing algorithm to identify the best set of compounds that can regulate DR-related pathways. Consequently, the proposed method enabled to predict new DR-inducing candidate combinations with fewer compounds and to successfully reproduce experimentally verified compounds inducing the direct conversion from fibroblasts to neurons or cardiomyocytes. The proposed method is expected to be useful for practical applications in regenerative medicine.

AVAILABILITY AND IMPLEMENTATION

The code supporting the current study is available at the http://labo.bio.kyutech.ac.jp/~yamani/comprendre.

SUPPLEMENTARY INFORMATION

Supplementary data are available at Bioinformatics online.

A review of protocols for human iPSC culture, cardiac differentiation, subtype-specification, maturation, and direct reprogramming

The methods for the culture and cardiomyocyte differentiation of human embryonic stem cells, and later human induced pluripotent stem cells (hiPSC), have moved from a complex and uncontrolled systems to simplified and relatively robust protocols, using the knowledge and cues gathered at each step. HiPSC-derived cardiomyocytes have proven to be a useful tool in human disease modelling, drug discovery, developmental biology, and regenerative medicine. In this protocol review, we will highlight the evolution of protocols associated with hPSC culture, cardiomyocyte differentiation, sub-type specification, and cardiomyocyte maturation. We also discuss protocols for somatic cell direct reprogramming to cardiomyocyte-like cells.

Manipulating Cardiomyocyte Plasticity for Heart Regeneration

Pathological heart injuries such as myocardial infarction induce adverse ventricular remodeling and progression to heart failure owing to widespread cardiomyocyte death. The adult mammalian heart is terminally differentiated unlike those of lower vertebrates. Therefore, the proliferative capacity of adult cardiomyocytes is limited and insufficient to restore an injured heart. Although current therapeutic approaches can delay progressive remodeling and heart failure, difficulties with the direct replenishment of lost cardiomyocytes results in a poor long-term prognosis for patients with heart failure. However, it has been revealed that cardiac function can be improved by regulating the cell cycle or changing the cell state of cardiomyocytes by delivering specific genes or small molecules. Therefore, manipulation of cardiomyocyte plasticity can be an effective treatment for heart disease. This review summarizes the recent studies that control heart regeneration by manipulating cardiomyocyte plasticity with various approaches including differentiating pluripotent stem cells into cardiomyocytes, reprogramming cardiac fibroblasts into cardiomyocytes, and reactivating the proliferation of cardiomyocytes.

MicroRNA Roles in Cell Reprogramming Mechanisms

Cell reprogramming is a groundbreaking technology that, in few decades, generated a new paradigm in biomedical science. To date we can use cell reprogramming to potentially generate every cell type by converting somatic cells and suitably modulating the expression of key transcription factors. This approach can be used to convert skin fibroblasts into pluripotent stem cells as well as into a variety of differentiated and medically relevant cell types, including cardiomyocytes and neural cells. The molecular mechanisms underlying such striking cell phenotypes are still largely unknown, but in the last decade it has been proven that cell reprogramming approaches are significantly influenced by non-coding RNAs. Specifically, this review will focus on the role of microRNAs in the reprogramming processes that lead to the generation of pluripotent stem cells, neurons, and cardiomyocytes. As highlighted here, non-coding RNA-forced expression can be sufficient to support some cell reprogramming processes, and, therefore, we will also discuss how these molecular determinants could be used in the future for biomedical purposes.

A biomimetic hydrogel culture system to facilitate cardiac reprogramming

Direct cardiac reprogramming, in which fibroblasts are converted into induced cardiomyocytes (iCMs) with cardiogenic transcription factors, may be a promising approach for myocardial regeneration. Here, we present a protocol for cardiac reprogramming using a handmade hydrogel culture system. This system can recapitulate substrate stiffness comparable to that of the native myocardium. This protocol features improved efficiency of cardiac reprogramming by generating threefold more beating iCMs on the Matrigel-based hydrogel culture system compared to that on conventional polystyrene dishes.

For complete details on the use and execution of this protocol, please refer to Kurotsu et al. (2020)

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Protocol for cardiac reprogramming using a soft hydrogel system

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Generation of beating iCMs with 3% efficiency on hydrogel culture

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Detailed approaches for generating Matrigel-based hydrogel culture systems

Recent Advances in Small Molecule Stimulation of Regeneration and Repair

Therapeutic approaches to stimulate regeneration and repair have the potential to transform healthcare and improve outcomes for patients suffering from numerous chronic degenerative diseases. To date most approaches have involved the transplantation of therapeutic cells, and while there have been a small number of clinical approvals, major hurdles exist to the routine adoption of such therapies. In recent years humans and other mammals have been shown to possess a regenerative capacity across multiple tissues and organs, and an innate regenerative and repair response has been shown to be activated in these organs in response to injury. These realisations have inspired a transformative approach in regenerative medicine: the development of new agents to directly target these innate regeneration and repair pathways. In this article we will review the current state of the art in the discovery of small molecule modulators of regeneration and their translation towards therapeutic agents, focussing specifically on the areas of neuroregeneration and cardiac regeneration.

Direct reprogramming as a route to cardiac repair

Ischemic heart disease is the leading cause of morbidity, mortality, and healthcare expenditure worldwide due to an inability of the heart to regenerate following injury. Thus, novel heart failure therapies aimed at promoting cardiomyocyte regeneration are desperately needed. In recent years, direct reprogramming of resident cardiac fibroblasts to induced cardiac-like myocytes (iCMs) has emerged as a promising therapeutic strategy to repurpose the fibrotic response of the injured heart toward a functional myocardium. Direct cardiac reprogramming was initially achieved through the overexpression of the transcription factors (TFs) Gata4, Mef2c, and Tbx5 (GMT). However, this combination of TFs and other subsequent cocktails demonstrated limited success in reprogramming adult human and mouse fibroblasts, constraining the clinical translation of this therapy. Over the past decade, significant effort has been dedicated to optimizing reprogramming cocktails comprised of cardiac TFs, epigenetic factors, microRNAs, or small molecules to yield efficient cardiac cell fate conversion. Yet, efficient reprogramming of adult human fibroblasts remains a significant challenge. Underlying mechanisms identified to accelerate this process have been centered on epigenetic remodeling at cardiac gene regulatory regions. Further studies to achieve a refined understanding and directed means of overcoming epigenetic barriers are merited to more rapidly translate these promising therapies to the clinic.

Skeletal muscle satellite cell-derived mesenchymal stem cells ameliorate acute alcohol-induced liver injury

Cultured human skeletal-muscle satellite cells have properties of mesenchymal stem cells (skeletal muscle satellite cell-derived mesenchymal stem cells, SkMSCs) and play anti-inflammatory roles by secreting prostaglandin E2 and hepatocyte growth factor (HGF). To evaluate the utility of SkMSCs in treating liver diseases, we determined whether SkMSCs could ameliorate acute liver and gut inflammation induced by binge ethanol administration. Binge drinking of ethanol led to weight loss in the body and spleen, liver inflammation and steatosis, and increased serum ALT and AST levels (markers of liver injury), along with increased IL-1β, TNF-α, and iNOS expression levels in mice. However, levels of these binge-drinking-induced indicators were reduced by a single intraperitoneal treatment of SkMSCs. Furthermore, levels of bacteria-derived lipopolysaccharide decreased in the livers and sera of ethanol-exposed mice after SkMSC administration. SkMSCs decreased the extent of tissue inflammation and reduced villus and crypt lengths in the small intestine after alcohol binge drinking. SkMSCs also reduced the leakage of blood albumin, an indicator of leaky gut, in the stool of ethanol-exposed mice. Alcohol-induced damage to human colonic Caco-2/tc7 cells was also alleviated by HGF. Therefore, a single treatment with SkMSCs can attenuate alcoholic liver damage by reducing inflammatory responses in the liver and gut, suggesting that SkMSCs could be used in cell therapy to treat alcoholic liver diseases.

Resuscitating the Field of Cardiac Regeneration: Seeking Answers from Basic Biology

Heart failure (HF) is one of the leading causes for hospital admissions worldwide. HF patients are classified based on the chronic changes in left ventricular ejection fraction (LVEF) as preserved (LVEF ≥ 50%), reduced (LVEF ≤ 40%), or mid-ranged (40% < LVEF < 50%) HFs. Treatments nowadays can prevent HFrEF progress, whereas only a few of the treatments have been proven to be effective in improving the survival of HFpEF. In this review, numerous mediators involved in the pathogenesis of HF are summarized. The regional upstream signaling and their diagnostic and therapeutic potential are also discussed. Additionally, the recent challenges and development in cardiac regenerative therapy that hold opportunities for future research and clinical translation are discussed.

Therapeutic Potential of Selected Medicinal Plants Against Carrageenan Induced Inflammation in Rats

The current study was aimed to analyze the therapeutic effect of selected medicinal plants, that is, Curcuma longa, Zingiber officinale, Trigonella graceum-foenum, Nigella sativa, and Syzygium aromaticum against carrageenan-induced oxidative stress and inflammation in rats. Phytochemical analysis revealed the presence of diverse range of bioactives. IC₅₀ values for antioxidant assays including DPPH (2,2-diphenyl-1-picrylhydrazyl), metal chelating, ABTS scavenging (2, 2^′-Azino-Bis-3-Ethylbenzothiazoline-6-Sulfonic Acid), β-carotene bleaching, and H₂O₂ (hydrogen peroxide) scavenging ranged from 37-294, 71-243.4, 69.66-191.8, 98.92-228.5, and 82-234.9 μg/mL, respectively. All tested plants extract were found active against tested pathogenic microorganisms with lowest minimum inhibitory concentrations. Oral administration of tested plants extracts in different doses (250, 500, and 1000 mg/kg b. w) did not exhibit any toxicological effects on hemato-biochemical profile of treated rats in comparison to control group rats. Further, plants extract exhibited considerable anti-inflammatory activity in rats paw inflammation and decreased cellular infiltration to inflammatory site in dose dependent manner. Pretreatment of animals with tested plants extract (100, 200, and 400 mg/kg b. w.) caused significant alteration in total antioxidants, oxidants, and enzymes activities in paw tissue homogenate and the effect was more pronounced at higher concentration (400 mg/kg b. w.). Results showed that tested plants extract are rich source of diverse classes of phenolics and have therapeutic potential against oxidative stress and inflammation.

Prostaglandin E2 EP receptors in cardiovascular disease: An update

This review article provides an update for the role of prostaglandin E2 receptors (EP1, EP2, EP3 and EP4) in cardiovascular disease. Where possible we have reported citations from the last decade although this was not possible for all of the topics covered due to the paucity of publications. The authors have attempted to cover the subjects of ischemia-reperfusion injury, arrhythmias, hypertension, novel protein binding partners of the EP receptors and their pathophysiological significance, and cardiac regeneration. These latter two topics bring studies of the EP receptors into new and exciting areas of research that are just beginning to be explored. Where there is peer-reviewed literature, the authors have placed particular emphasis on clinical studies although these are limited in number.

Improving Cardiac Reprogramming for Heart Regeneration in Translational Medicine

Direct reprogramming of fibroblasts into CM-like cells has emerged as an attractive strategy to generate induced CMs (iCMs) in heart regeneration. However, low conversion rate, poor purity, and the lack of precise conversion of iCMs are still present as significant challenges. In this review, we summarize the recent development in understanding the molecular mechanisms of cardiac reprogramming with various strategies to achieve more efficient iCMs. reprogramming. Specifically, we focus on the identified critical roles of transcriptional regulation, epigenetic modification, signaling pathways from the cellular microenvironment, and cell cycling regulation in cardiac reprogramming. We also discuss the progress in delivery system optimization and cardiac reprogramming in human cells related to preclinical applications. We anticipate that this will translate cardiac reprogramming-based heart therapy into clinical applications. In addition to optimizing the cardiogenesis related transcriptional regulation and signaling pathways, an important strategy is to modulate the pathological microenvironment associated with heart injury, including inflammation, pro-fibrotic signaling pathways, and the mechanical properties of the damaged myocardium. We are optimistic that cardiac reprogramming will provide a powerful therapy in heart regenerative medicine.

Bioengineering Methods in MicroRNA-Mediated Direct Reprogramming of Fibroblasts Into Cardiomyocytes

Ischemic heart disease is the major cause of mortality worldwide. Despite the most recent pharmacological progresses, cardiac regeneration is yet not possible, and heart transplantation is the only therapeutic option for end-stage heart failure. Traditional cardiac regenerative medicine approaches, such as cell therapies and tissue engineering, have failed in the obtainment of human functional cardiac tissue, mainly due to unavailability of high quantities of autologous functional cardiomyocytes (CMs), low grafting efficiency, and/or arrhythmic events. Direct reprogramming (DR) of fibroblasts into induced CMs (iCMs) has emerged as a new promising approach for myocardial regeneration by in situ transdifferentiation or providing additional CM source for cell therapy. Among available DR methods, non-viral transfection with microRNAs (miRcombo: miR-1, miR-133, miR-208, and miR-499) appears promising for future clinical translation. MiRcombo transfection of fibroblasts could be significantly improved by the development of safe nanocarriers, efficiently delivering their cargo to target cells at the required stoichiometric ratio and overall dose in due times. Newly designed in vitro 3D culture microenvironments, providing biomimetic biophysical and biochemical stimuli to miRcombo-transfected cells, significantly increase the yield of fibroblast transdifferentiation into iCMs, enhancing CM gene expression. Epigenetic regulation of gene expression programs, critical to cell lineage commitment, can also be promoted by the administration of specific anti-inflammatory and anti-fibrotic soluble factors, helping in suppressing fibroblast signature. The aim of this mini-review is to introduce the readers to a relatively unknown field of cardiac research integrating bioengineering tools as relevant for the progress of miRNA-mediated cardiac DR.

Betulinic acid exerts antigenotoxic and anticarcinogenic activities via inhibition of COX-2 and PCNA in rodents

Phytochemicals have been suggested as an effective strategy for cancer prevention. Within this context, triterpene betulinic acid (BA) exhibits several biological properties but its chemopreventive effect has not been fully demonstrated. The present study investigated the antigenotoxic potential of BA against doxorubicin (DXR)-induced genotoxicity using the mouse peripheral blood micronucleus assay, as well as its anticarcinogenic activity against 1,2dimethylhydrazine (DMH)-induced colorectal lesions in rats. Micronuclei (MN) assay and aberrant crypt foci assay were used to assess the antigenotoxic and the anticarcinogenic potential, respectively. The molecular mechanisms underlying the anticarcinogenic activity of BA were evaluated by assessing anti-inflammatory (COX-2) and antiproliferative (PCNA) pathways. The results demonstrated that BA at the dose of 0.5 mg/kg bodyweight exerted antigenotoxic effects against DXR, with a reduction of 70.2% in the frequencies of chromosomal damage. Animals treated with BA showed a 64% reduction in the number of preneoplastic lesions when compared to those treated with the carcinogen alone. The levels of COX-2 and PCNA expression in the colon were significantly lower in animals treated with BA and DMH compared to those treated with the carcinogen alone. The chemopreventive effect of BA is related, at least in part, to its antiproliferative and anti-inflammatory activity, indicating a promising potential of this triterpene in anticancer therapies, especially for colorectal cancer.

Advanced Technologies to Target Cardiac Cell Fate Plasticity for Heart Regeneration

The adult human heart can only adapt to heart diseases by starting a myocardial remodeling process to compensate for the loss of functional cardiomyocytes, which ultimately develop into heart failure. In recent decades, the evolution of new strategies to regenerate the injured myocardium based on cellular reprogramming represents a revolutionary new paradigm for cardiac repair by targeting some key signaling molecules governing cardiac cell fate plasticity. While the indirect reprogramming routes require an in vitro engineered 3D tissue to be transplanted in vivo, the direct cardiac reprogramming would allow the administration of reprogramming factors directly in situ, thus holding great potential as in vivo treatment for clinical applications. In this framework, cellular reprogramming in partnership with nanotechnologies and bioengineering will offer new perspectives in the field of cardiovascular research for disease modeling, drug screening, and tissue engineering applications. In this review, we will summarize the recent progress in developing innovative therapeutic strategies based on manipulating cardiac cell fate plasticity in combination with bioengineering and nanotechnology-based approaches for targeting the failing heart.

Atrial Natriuretic Peptide31-67: A Novel Therapeutic Factor for Cardiovascular Diseases

The characterization of the cardiac hormone atrial natriuretic peptide (ANP_99–126), synthesized and secreted predominantly by atrial myocytes under stimulation by mechanical stretch, has established the heart as an endocrine organ with potent natriuretic, diuretic, and vasodilating actions. Three additional distinct polypeptides resulting from proteolytic cleavage of proANP have been identified in the circulation in humans. The mid-sequence proANP fragment 31–67 (also known as proANP_31–67) has unique potent and prolonged diuretic and natriuretic properties. In this review, we report the main effects of this circulating hormone in different tissues and organs, and its mechanisms of actions. We further highlight recent evidence on the cardiorenal protective actions of chronic supplementation of synthetic proANP_31–67 in preclinical models of cardiorenal disease. Finally, we evaluate the use of proANP_31–67 as a new therapeutic strategy to repair end-organ damage secondary to hypertension, diabetes mellitus, renal diseases, obesity, heart failure, and other morbidities that can lead to impaired cardiac function and structure.

Cardiac regeneration by direct reprogramming in this decade and beyond

Japan faces an increasing incidence of heart disease, owing to a shift towards a westernized lifestyle and an aging demographic. In cases where conventional interventions are not appropriate, regenerative medicine offers a promising therapeutic option. However, the use of stem cells has limitations, and therefore, “direct cardiac reprogramming” is emerging as an alternative treatment. Myocardial regeneration transdifferentiates cardiac fibroblasts into cardiomyocytes in situ.

Three cardiogenic transcription factors: Gata4, Mef2c, and Tbx5 (GMT) can induce direct reprogramming of fibroblasts into induced cardiomyocytes (iCMs), in mice. However, in humans, additional factors, such as Mesp1 and Myocd, are required. Inflammation and immune responses hinder the reprogramming process in mice, and epigenetic modifiers such as TET1 are involved in direct cardiac reprogramming in humans. The three main approaches to improving reprogramming efficiency are (1) improving direct cardiac reprogramming factors, (2) improving cell culture conditions, and (3) regulating epigenetic factors. miR-133 is a potential candidate for the first approach. For the second approach, inhibitors of TGF-β and Wnt signals, Akt1 overexpression, Notch signaling pathway inhibitors, such as DAPT ((S)-tert-butyl 2-((S)-2-(2-(3,5-difluorophenyl) acetamido) propanamido)-2-phenylacetate), fibroblast growth factor (FGF)-2, FGF-10, and vascular endothelial growth factor (VEGF: FFV) can influence reprogramming. Reducing the expression of Bmi1, which regulates the mono-ubiquitination of histone H2A, alters histone modification, and subsequently the reprogramming efficiency, in the third approach. In addition, diclofenac, a non-steroidal anti-inflammatory drug, and high level of Mef2c overexpression could improve direct cardiac reprogramming.

Direct cardiac reprogramming needs improvement if it is to be used in humans, and the molecular mechanisms involved remain largely elusive. Further advances in cardiac reprogramming research are needed to bring us closer to cardiac regenerative therapy.

In vivo reprogramming as a new approach to cardiac regenerative therapy

Cardiovascular diseases are a common cause of death worldwide. Adult cardiomyocytes have limited regenerative capacity after injury, and there is growing interest in cardiac regeneration as a new therapeutic strategy. There are several limitations of induced pluripotent stem cell-based transplantation therapy with respect to efficiency and risks of tumorigenesis. Direct reprogramming enables the conversion of terminally differentiated cells into target cell types using defined factors. In most cardiac diseases, activated fibroblasts proliferate in the damaged heart and contribute to the progression of heart failure. In vivo cardiac reprogramming, in which resident cardiac fibroblasts are converted into cardiomyocytes in situ, is expected to become a new cardiac regenerative therapy. Indeed, we and other groups have demonstrated that in vivo reprogramming improves cardiac function and reduces fibrosis after myocardial infarction. In this review, we summarize recent discoveries and developments related to in vivo reprogramming. In addition, issues that need to be resolved for clinical application are described.

Environmental factors influence somatic cell reprogramming to cardiomyocyte-like cells

Direct cardiac reprogramming, which refers to somatic cell (i.e. fibroblast) fate conversion to cardiomyocyte-like cell without transitioning through an intermediate pluripotent state, provides a novel therapeutic strategy for heart regeneration by converting resident cardiac fibroblasts to cardiomyocytes in situ. However, several limitations need to be addressed prior to clinical translation of this technology. They include low efficiency of reprogramming, heterogeneity of starting fibroblasts, functional immaturity of induced cardiomyocytes (iCMs), virus immunogenicity and toxicity, incomplete understanding of changes in the epigenetic landscape as fibroblasts undergo reprogramming, and the environmental factors that influence fate conversion. Several studies have demonstrated that a combination of enforced expression of cardiac transcription factors along with certain cytokines and growth factors in the presence of favorable environmental cues (including extracellular matrix, topography, and mechanical properties) enhance the efficiency and quality of direct reprogramming. This paper reviews the literature on the influence of the microenvironment on direct cardiac reprogramming in vitro and in vivo.

Immunological Responses to Envenomation

Venoms are complex mixtures of toxic compounds delivered by bite or sting. In humans, the consequences of envenomation range from self-limiting to lethal. Critical host defence against envenomation comprises innate and adaptive immune strategies targeted towards venom detection, neutralisation, detoxification, and symptom resolution. In some instances, venoms mediate immune dysregulation that contributes to symptom severity. This review details the involvement of immune cell subtypes and mediators, particularly of the dermis, in host resistance and venom-induced immunopathology. We further discuss established venom-associated immunopathology, including allergy and systemic inflammation, and investigate Irukandji syndrome as a potential systemic inflammatory response. Finally, this review characterises venom-derived compounds as a source of immune modulating drugs for treatment of disease.

Inhibition of EZH2 primes the cardiac gene activation via removal of epigenetic repression during human direct cardiac reprogramming

Cardiovascular disease, until now, is still the leading cause of death in the United States. Due to the limited regenerative capacity of adult hearts, the damage caused by heart injury cannot be reversed and eventually progress into heart failure. In need of cardiovascular disease treatment, many therapies aimed at either cell transplantation or cell regeneration have been proposed. Direct reprogramming of somatic cells into induced cardiomyocytes (iCMs) is considered to be a promising strategy for regenerative medicine. The induction of cardiomyocytes from non-myocytes can be achieved efficiently via ectopic expression of reprogramming factors both in vitro and in vivo in the mouse model, however, the generation of human induced cardiomyocyte-like cells (hiCMs) remains challenging. The inefficiency of hiCMs production called for the identification of the additional epigenetic memories in non-myocytes which might be damping the hiCM reprogramming. Here, we conducted an unbiased loss-of-function screening focusing on epigenetic regulators and identified enhancer of zeste homolog 2 (EZH2) as an important epigenetic barrier during hiCM reprogramming. We found that the removal of EZH2 via genetic knockdown or treatment of EZH2 selective degrader significantly increased the hiCM reprogramming efficiency and led to profound activation of cardiac genes and repression of collagen and extracellular matrix genes. Furthermore, EZH2 inhibitors targeting its catalytic activity also promotes hiCM reprogramming, suggesting that EZH2 may restrain cardiac conversion through H3K27me3-mediated gene repression. Indeed, genomic profiling of H3K27me3 revealed a subset of cardiac genes that remain repressed with high levels of H3K27me3 despite of the delivery of the reprogramming factors. Inhibition of EZH2, however, leads to reduced H3K27me3 occupancy and robust activation of these cardiac genes. Taken together, our data suggested that EZH2 inhibition facilitates the activation of cardiac genes in fibroblasts and eases the production of hiCMs.

Cancer-associated fibroblasts activated by miR-196a promote the migration and invasion of lung cancer cells

Fibroblasts in the tumor microenvironment, known as cancer-associated fibroblasts (CAFs), promote the migration, invasion, and metastasis of cancer cells when they are activated through diverse processes, including post-transcriptional regulation by microRNAs (miRNAs). To identify the miRNAs that regulate CAF activation, we used NanoString to profile miRNA expression within normal mouse lung fibroblasts (LFs) and CAFs. Based on NanoString profiling, miR-196a was selected as a candidate that was up-regulated in CAFs. miR-196a-overexpressed LFs (LF-196a) promoted the migration and invasion of lung cancer cells in co-culture systems (Transwell migration and spheroid invasion assays). ANXA1 was confirmed as a direct target of miR-196a, and adding back ANXA1 to LF-196a restored the cancer cell invasion promoted by miR-196a. miR-196a increased CCL2 secretion in fibroblasts, and that was suppressed by ANXA1. Furthermore, blocking CCL2 impeded cancer spheroid invasion. In lung adenocarcinoma patients, high miR-196a expression was associated with poor prognosis. Collectively, our results suggest that CAF-specific miR-196a promotes lung cancer progression in the tumor microenvironment via ANXA1 and CCL2 and that miR-196a will be a good therapeutic target or biomarker in lung adenocarcinoma.